Tension shoe mounting for projectors



Nov. 30, 1948. E. J. wlENKE TENSION SHOE MOUNTING FOR PROJECTORS el QNFiled. Feb. l5, 1945 Patented Nov. 30, 1948 TENSION SHOE MOUNTING FORPROJ ECTORS Emil J. Wienke, Glen Ellyn, Ill., assigner to Motiograph,Chicago, Ill., a limited partnership Application February 15, 1946,Serial No. 647,938

4 Claims. (Cl. 88-17) The present invention relates to motion pictureprojectors, and particularly to the mounting and operation of the iilmtension shoe which presses the iilm against the guides of the iilmaperture plate and provides the lnecessary frictional drag on the film.It is the principal purpose of this invention to provide a novel tensionshoe support whereby the tension shoe itself may easily be given any oneof a plurality of adjustments to varyl the tension that is applied tothe lm, and the shoe itself may be readily removed at any time.

t is a further purpose of my invention to provide a film tension shoesupport of the type above referred to with a novel mounting and lockingmeans for removably locking the shoe to the support.

It is a further purpose of my invention to provide a novel springbacking construction :for the lm tension shoe that can be utilized togive more or less spring pressure to the shoe by a simple manualadjustment.

The nature and advantages of my invention will appear more fully fromthe following description and the accompanying drawings wherein apreferred form of the invention is shown. It should be understood,however, that the drawings and description are illustrative only, andshould not be considered as limiting the invention except insofar as itis limited by the claims.

l'n the drawings:

Figure l is a side view partially in section of the hlm tension shoesupport which embodies my invention,

Figure 2 is a sectional view taken on the line 2-2 of Figure l withcertain parts broken away,

Figure 3 is a sectional view taken on the line 3 3 of Figure 2, and

Figure 4 is a prospective view of the film tension shoe.

Referring now to the drawings, the present invention is directed tofeatures of a lm tension shoe support which forms part of the mechanismdescribed in my pending application, Serial Number 647,937 filedFebruary i5, 1946, for motion picture projector wherein the severalparts of a motion picture projector that are concerned with the clampingof the film in position at the light aperture for the transmission ofthe image from the film through the projector, constitute a single unitthat is mounted in the projector housing in such fashion as to becapable of extremely accurate mounting and susceptible of readyreplacement of the entire unit or any one of the component parts withoutloss of the original accuracy of position with respect to the light axison the projector.

The film tension shoe support comprises a bracket 5 which is movablymounted by upper and lower sets 6 and 1 of ball bearings that ride inV-shaped grooves of two guides 8 and 9 that are provided. upon anassembly base l0 which is mounted in the projector housing. The ballbear* ings are held in place by suitable plates II and l2 which arecarried by the bracket 5. The bracket 5 supports a frame I3 which inturn provides the support for a lm tension shoe I4. The

nlm `tension shoe is shown in Figure 4 of the draw-` ings, as comprisinga rectangular frame work with two side pressure rails I5 and I6 that areadapted to engage the film and upper and lower cross pieces I'I and I8that connect the rails. This leaves an open space I9 which is locatedopposite the light aperture through which light is transmitted to thefilm. The cross pieces I1 and I8 carry two mounting pins 20 and 2l whichhave enlarged heads 22 and 23 thereon, somewhat conical at their cuterends. The frame I3 has a front face plate 24 that has an upper key holeslot 25 to receive the pin 20, and a lower key hole slot 26 to receiveAthe pin 2 I. This plate 24 has an aperture 21 which is aligned with thelight aperture of the film guide plate. The tension shoe i4 can beinserted and removed from the plate 24 by aligning the heads 22 and 23with the upper enlarged portions of the key hole slots 25 and 2B. Whenthe shoe is-positioned as shown in Figure 3, a locking pin 28 is pressedforward by its spring 29 to extend over the head 22 of the pin 20, thusholding the tension shoe in position. In order to remove the tensionshoe, the pin 28 has to be drawn back by a handle 3G, after which theshoe can be lifted to align the heads 22 and 23 with the large parts ofthe key hole slots.

The film tension shoe is yleldingly pressed forward by means oi twoyokes 3| and 32. These yokes have end portions such as those indicatedat 33 and 34 extending through corresponding apertures in the plate 24.The yokes are pressed forwardly by leaf springs 35 and 36. The leafsprings 35 and 36 are mounted upon the pivot pin 31, the lower end ofwhich is pivoted by a screw 38 in an aperture 39 at the bottom of theframe I3. The upper end of the pin 31 is similarly pivoted by a screw 40in an aperture 4I of the frame I'3. In order -to hold the springs 35 and36 against the yokes 3l and 32, I provide an arm 42 on the part 31 and acam 43 by which the arm may be pushed more or less forward, that is,

r toward the tension shoe to in turn swing the pin il? and the springs35 and 36 against the yokes with a greater or lesser pressure. It willbe noted that the cam i3 is pivoted by a suitable ear 44 on the framei3. This ear is provided with a pointer to cooperate with suitablegraduations provided on the earn 53. The cam ha-s a plurality of notchesll and "38 therein located at difierent distances from the cam pivot soas to provide the desired adjustment. A finger piece 19 is .secured toan ear 59 of the cam for operating.

The three notches dll, il and 48 provide a high tension of the springs35 and 36, an intermediate or standard running tension and anextremelylow tension.. In some instances it is necessary to obtain atension between the three notches, and the cam can be so shaped as toprovide a different tension between these three Idei-"mite stop points.It is obvious that more or less stop points can be provided within thescope of my invention.

The mounting of the tension shoe permits ready removal of it since allthat is necessary to remove it is to pull back the pin 28 and then liftthe shoe until the heads 22 and 23 can be pulled through the key holeslots. The attachment and removal of the tension shoe does not affectthe spring adjustment in any way.

Having thus described my invention, I claim:

l. A iilrn tension shoe mount for motion picture machines comprising aframe including a front face plate, a film tension shoe, cooperatingmembers on the plate and shoe mounting the shoe on the plate for limitedmovement toward and away from the plate and limited movement of the shoein a direction parallel to the plate, said members being separable whenthe shoe is moved parallel to the plate to a point near one limit of itsmovement parallel to the plate, and a spring pressed lock normallyholding the shoe at its other limit of movement parallel to the plate.

2. A film tension shoe mount for motion picture machines comprising aframe including a front :face plate, a film tension shoe, cooperatingmembers on the plate and shoe mounting the shoe on the plate for limitedmovement toward and away from the plate, upper and lower yokes carriedin said frame and having portions eX- tending through the plate andengaging the shoe to press it away from the plate, leaf springs pressingon said yokes, a support for said springs pivoted in the frame, andmeans for turning said support on its pivots to vary the tension of saidsprings, said last named means comprising a pin projecting from said-support and a manually adinstable cam on the frame engaging said pin.

3A A iilm tension shoe mount for motion picture machines comprising aframe including a front face plate, a iilm tension shoe, cooperatingmembers on the plate and shoe mounting the shoe on theplate'for limitedmovement toward and away from the plate, and means mounted in the framefor yieldingly pressing the tension shoe away from the plate, said meansincluding spaced members projecting through the plate, spring meansurging said members outward toward the shoe, a member carrying saidspring means and pivoted in the frame, and means for adjusting saidmember on its pivot to vary the tension on said springs.

fi. A lm ten-sion shoe mount for motion picture machines Comprising aframe including a front face plate having a light aperture, a lm tensionshoe in front of said plate, cooperating members on the plate and shoemounting the shoe on the plate for limited movement toward and away fromthe plate, and said plate having an upper pair of laterally `spacedapertures therein above the light aperture and a lower pair of laterallyspaced apertures therein below the light aperture, upper and lower yokescarried in said frame and having their free ends extending through thepairs of apertures and engaging the back of said lrn tension shoe topress it toward its outer limit of movement, a pin pivoted in the/fframe, spring arms fixed to the pin and bearing against the yokes topress them toward the shoe, an arm xed to the pin and extendinglaterally from it, a cam plate pivoted on said frame and extending intothe path of the pin, said cam plate having notches on its pin engagingsurface for retaining the cam in fixed position.

EMIL J. WIENKE.

REFERENCES 'CITED The following 'references are of record in the le ofthis patent:

U N ITED STATES PATENTS Number Name Date 2,140,738 Fitz Dec. 20, 19382,211,826 Kindelman-n, et al. Aug. 20, 1940 2,246,970 Brenkert June 24,1941

